Microwave power divider

ABSTRACT

A stripline power divider is disclosed wherein three center conductors are joined at a common junction and the ground planes have slots formed therein adjacent to the common junction. Reflections resulting from mismatched impedances terminating a pair of the center conductors radiate through the slots. A load material is disposed over the slots to absorb any such radiating reflections.

United States Patent Plunk et al.

MICROWAVE POWER DIVIDER Inventors: Troy E. Plunk, Bedford; Robert L.

Moran, Franklin, both of Mass.

Assignee: Raytheon Company, Lexington,

Mass.

Filed: Apr. 20, 1973 Appl. No.: 353,170

US. Cl 333/9, 333/33, 333/81 A, 333/84 R Int. Cl HOlp 3/08, HOlp 5/12, H03h 7/38 Field of Search 333/l, 6, 8, 9, 10, ll, 333/84 R, 84 M, 22 R, 33, 81 A References Cited UNITED STATES PATENTS 3/l959 Butler 333/84 M June 4, 1974 3,209,284 9/1965 Hast 333/22 R X 3,348,l7() l0/l967 Barker 333/22 R 3,573,670

4/l97l Skobern 333/33 Primary Examiner.lames W. Lawrence Assistant Examiner-Marvin Nussbaum Attorney, Agent, or FirmRichard M. Sharkansky; Joseph D. Pannone; Phillip J. McFarland 5 7] ABSTRACT A stripline power divider is disclosed wherein three center conductors are joined at a common junction and the ground planes have slots formed therein adjacent to the common junction. Reflections resulting from mismatched impedances terminating a pair of the center conductors radiate through the slots. A load material is disposed over the slots to absorb any such radiating reflections.

5 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION This invention relates generally to microwave power dividers and moreparticularly to stripline power dividers.

As is known in. the art, microwave power dividers have been, used in a wide variety of applicationsfor many years. Many such power dividers generally include three arms or ports, one armsometimes referred to as an input port and the other arms sometimes referred to as a pair of output ports. If the loads terminating such output ports are mismatched reflections will exist within the power divider.

One application for a microwave, power divider is in a corporate feed phasedarray antenna. In such an antenna a plurality of radiating elements are coupled to a common feed through an arrangement of microwave power dividers as described in Radar Handbook, Merrill I; Skolnik, McGraw-HillBook Company, I970 on pages 1 1-52 and l l-53. lnsuch arrangement generally each pair of output ports of each-power divider used therein is coupled to different; ones of the radiating elements. As is also known, because of mutual coupling between the radiating elements each one thereof may be considered as havingan impedance including the effect of the mutual coupling. Therefore, if the mutual coupling differs between the radiatingelements, as is generally the casein any practical application, the output ports of each pair of powerdividers will not be properly matched to its radiating element and unwanted reflections will occur. These unwanted -reflec-.

tions result indegradationof the radiation pattern of the phased array antenna byway of unwantedsidelobes.

' As is also known in the art, in order to reduce the size and weight ofa corporate feed phased array antenna, stripline power dividers are sometimes used. Such powerdividers aregenerally' characterized as a printed circuit within a dielectricmaterial to formthree center conductors (called arms or ports the outersurfaces of such material being covered with a conducting material to form a pair of ground planes.

One known stripline power divider is sometimes called a split-tee power divider and is described in an article entitIed SpIit-Tee Power. Divider by L. I. Parad and R. L. Moynihan, IEEE Transactions on Microwave Theory and Techniques, January 1965, pages 91-95. In such power divider an isolation resistor is included within the dielectric material. Such resistor'is connected between the pair of output arms, thereby makingit necessary to spatially separate such arms fromeach other at the resistor. Theoretically, however, such armsshould be contiguous at the resistor for proper isolation andpowerdivision. Further, because the isolation resistor. disposed'within the dielectric material may not be designed to dissipate relatively large amounts of power, thepower capacity of such known stripline power divider is'relat-ively low.

SUMMAR YfOF THE INVENTION It is another object *of theinventionto providea stripline power divider havinggimproved reflected power dissipation characteristics.

These and other objects of the invention are attained generally by providing a stripline power divider wherein three center conductors are joined at a common junction and the ground planes have slots formed therein adjacent the common junction. Load material, disposed over the slots, is also provided.

BRIEF DESCRIPTION OF THE DRAWING Referring now to the FIGURE, a stripline power divider is shown to include a center conductor circuit 10 disposed within adielectric material, such material here made up of two sectionsl2, 14. The circuit 10 is v formed of a conductingmaterial, here copper, deposited or printed in any conventional manner on a portion of one of the sections of the dielectric material, here section 14. Circuit 10 includes three center conductors or arms 16, 18, 20, one end of each of the arms being connected or joined at-a common junction 22 and the other end of each of the arms being coupled to suitable connecting terminals (not shown). For example, such connecting terminalsmay be conventional stripline to coaxial cable connectors. Or, for example, such con- =necting terminals may be other stripline circuitry coupled to the power divider. Arms 16 and 18 may be considered as the pairof output ports of the power divider and arm 20 may be considered as the input port of the power divider. Common'junction 22 includes a match; ing region (not numbered) here made up of two sections 21, 23, as shown. Such matching section provides for impedance matching between the impedance associated .with arm 20 and the impedances associated with arms 16 and 18. The lengths of sections 21 and 23 are designated a and b" respectively as shown.

The outer surfaces 24, 261of each one of the sections l2, 14 have deposited or printed on a portion thereof a conducting material, here copper, to form ground planes for circuit 10; Slots 28, 30are formed in the conducting material printedon outer surfaces 24, 26' respectively as shown. Such slots are disposed over a portion of the common junction 22 so that reflected energy resulting from mismatched impedance terminations (not shown) of the arms 18, 20 radiates through such slots. Each one of the slots 28, 30 may therefore be considered as analogous to the port formed by the E-arm of a conventional Magic Tee hybrid junction.

Load materials 32, 34,- here of circular shape and made of alossy substance, here a carbon loaded epoxy, are'disposed over the slots 28, 30 as shown and serve to absorb the above mentioned reflections which pass through such slots. Such load materials 32, 34 are affixed to the conducting. material printed on the outer surfaces 24,26by any suitablemeans, as an epoxy (not shown).

Conducting material 36, 38, here copper, is-deposited or printed (as by electroplating) onthe loadmaterials 32', 34 as shown, to form parallel plate regions between conducting materials 24 and 32 and between conducting materials 26 and 38. That is, energy radiating through slots 28, 30 are confined, because of the parallel slot regions, to propagate through the loads 32, 34 and thereby be absorbed by such loads.

The stripline power divider shown in the FIGURE has been built at X-band and, for equal power division between arms l6, 18 may be characterized by the following parameters:

Impedance of arms l6, 18, 20 50 ohms Impedance of section 2] 25 ohms Impedance of section 23 35 ohms Dielectric constant of dielectric material, 6 2.32

Dimension of slots 28, 30 0.055 in. X 0.47 in.

Orientation of slots 28, 30 symmetrical with respect to arms l6, 18, 20

Diameter of load materials 32, 34 0.650 in.

Thickness of dielectric material 0.125 in.

Thickness of load materials 32, 34 0.060 in.

Dimension 0.] in.

Dimension 37 b 0.1 in.

Having described a preferred embodiment of the invention, it will now be immediately apparent to those having ordinary skill in the art that the power divider may be designed for other than equal power division between arms 16 and 18 by adjusting the impedance ratio of such arms. Further, the shape of common junction 22 may be changed from the T-shape shown to, say, a Y-shape in order to obtain a desired impedance matching between the arms. Further, the size and orientation of slots 28, 30 may be adjusted in accordance with the impedance terminating each of the arms. It is felt, therefore, that this invention should not be restricted to its disclosed embodiments but rather should be limited only by the spirit and scope of the appended claims.

What is claimed is:

l. A microwave power divider comprising:

a. a dielectric material;

b. a ground plane deposited on a portion of each side of the dielectric material, each ground plane having a slot formed therein; and

c. three center conductors disposed within the dielectric material, such conductors being joined at a common junction, the slot being positioned adjacent to the junction.

2. The microwave power divider recited in claim 1 including additionally a pair of load materials terminating the slots.

3. The microwave power divider recited in claim 2 including conducting materials disposed on the pair of load materials to form a parallel plate region within the load materials.

4. A microwave power divider comprising:

a. a dielectric material; I

b. ground planes deposited on each side of the dielectric material, one of such ground planes having a slot formed therein;

0. three center conductors disposed within the dielectric material, such conductors being joined at a common junction, the slot being positioned adjacent to the junction.

5. The power divider recited in claim 4 including additionally a load material terminating the slot. 

1. A microwave power divider comprising: a. a dielectric material; b. a ground plane deposited on a portion of each side of the dielectric material, each ground plane having a slot formed therein; and c. three center conductors disposed within the dielectric material, such conductors being joined at a common junction, the slot being positioned adjacent to the junction.
 2. The microwave power divider recited in claim 1 including additionally a pair of load materials terminating the slots.
 3. The microwave power divider recited in claim 2 including conducting materials disposed on the pair of load materials to form a parallel plate region within the load materials.
 4. A microwave power divider comprising: a. a dielectric material; b. ground planes deposited on each side of the dielectric material, one of such ground planes having a slot formed therein; c. three center conductors disposed within the dielectric material, such conductors being joined at a common junction, the slot being positioned adjacent to the junction.
 5. The power divider recited in claim 4 including additionally a load material terminating the slot. 